Guidance for and/or confirmation of a procedure being carried out by (or partly by) an operator may be facilitated in a number of ways. For example, a paper document such as a maintenance checklist may be prepared beforehand, with instructions for each event that is to be executed, a box to be checked or initialed by the operator to confirm events have been executed, blanks to record data or comments associated with events in the procedure, etc. However, such static instructions and documentation may exhibit limitations in at least some instances.
For example, linear paper checklists may not closely correspond with procedures that may be non-linear. As a more concrete example, in performing maintenance on complex systems such as aircraft engines, the appropriate procedure may branch, loop back, or be otherwise non-linear depending on the condition of the engine itself, a paper checklist may not accommodate adding a sequence to lubricate some engine component if it is determined to be necessary upon inspection, skipping replacement of a presumed worn part if the part is in fact not worn, etc.
In addition, simple paper checklists or similar may be limited in terms of the guidance that may be offered, and/or the feedback that may be accepted. To continue the example above, a paper checklist may lack space for detailed drawings showing the individual engine components to be serviced or for a specific maintenance history for the particular engine being serviced, may not support evidence or confirmation that a new component has been installed properly beyond a check-off, sign-off, etc.
Furthermore, static guidance and feedback may not adapt well to changing conditions. Modest changes to an engine or to “best practices” in engine maintenance may render entire checklists (or at least significant portions thereof) obsolete. Appropriate procedures may even vary depending on the age or history of a particular engine, e.g. a 10-year-old engine may be prone to different maintenance issues than a nominally-identical newer engine, an engine that has shown an unusual history of wear to certain components may benefit from greater attention to those or related components for that specific engine, etc.